(b.1724-d.1804) German professor of metaphysics at Konigsberg, who perhaps has been the most powerful influence on modern Western philosophical thought.
Kant is known for his theory of transcendental idealism (that we bring innate forms and concepts to the raw experience of the world, which we would otherwise be completely ignorant of). His revolutionary book, 'Critique of Pure Reason' includes this thought experiment: Try to imagine something that exists in no time and has no extent in space. The human mind cannot produce such an idea—time and space are fundamental forms of perception that exist as innate structures of the mind. Nothing can be perceived except through these forms, and the limits of physics are the limits of the fundamental structure of the mind.

Kant's deontological, duty-based moral system is based on his categorical imperative, and it's three formulations: those of Universal Law, Humanity, and Automony.

Kant's ideas have been both copied and condemned, though there is no denying his influence on modern thought. Most philosophers, from Marx to Nietzsche to Wittgenstein have had to either react to the ideas of Kant in one way or another.

Kant also formulated the first modern theory of solar system creation, known as the Kant-Laplace hypothesis.